I'tikaf (Arabic: الاعتكاف) is a mustahab (recommended) worship in Islam that consists of at least three days of fasting in a masjid. Although there is no specific time to perform I'tikaf during a year, the last ten days of Ramadan, as the Prophet (s) did so, are the most recommended days to do it.
There is no information whether the Prophet (s) performed I'tikaf in Masjid al-Haram before Hijra (emigration to Medina). However, in his first year in Medina, he performed I'tikaf in the first ten days of the month of Ramadan, the next year in the second ten days and afterward in the last ten days of the month of Ramadan. A tent was set up for him in the mosque during these days.
There is no special time for I'tikaf. However according to hadiths, the Prophet (s) did it in the month of Ramadan; thus this month is the best time for it, especially the last ten days. Based on these hadiths, I'tikaf during these days is very Mustahab (highly recommended) although it remains Mustahab in other times. Nowadays, holding the ritual of I'tikaf during Ayyam al-Bid of the month of Rajab is very prevalent in Iran.
According to Shi'a jurisprudence, duration of I'tikaf must not be less than three days (from the dawn of the first day to the sunset of the third day).
According to some hadiths, Masjid al-Haram, al-Masjid al-Nabawi, Masjid al-Kufa and the mosque of Basra are the only places for I'tikaf, but according to some others, every Masjid al-Jami' (the main and usually biggest mosque of a city) or every mosque that a just Imam has performed Jum'ah or Congregational prayer in it is suitable for I'tikaf. Read more...